Abstract
Background: Programmed death-ligand 1 (PD-L1) is an immune checkpoint molecule expressed by cancer cells. Previous studies have demonstrated the prognostic role of PD-L1 expression in patients with small cell lung cancer (SCLC), where the results were inconsistent. Therefore, we conducted a meta-analysis to identify the prognostic impact of PD-L1 on SCLC.Methods: We searched the PubMed, Embase, ISI Web of Science, and Cochrane Library databases for articles published before and on March 2nd, 2020. Data of PD-L1 expression in tumor cells detected using immunohistochemistry methods were extracted for analysis. Pooled hazard ratios (HRs) with confidence intervals (CIs) and odds ratios (ORs) with 95% CIs were calculated to assess the correlations among PD-L1, overall survival (OS), and clinicopathological factors.Results: Nine studies of 921 patients published between 2015 and 2019 were included in this meta-analysis. The pooled data (HR = 0.91, 95% CI = 0.46–1.80, p = 0.787) indicated that PD-L1 expression is not a significant predictor of poor OS. Moreover, the results also revealed that PD-L1 expression is not significantly associated with gender (OR = 1.12, 95% CI = 0.73–1.74, p = 0.601), age (OR = 1.15, 95% CI = 0.58–2.30, p = 0.683), pN stage (OR = 0.65, 95% CI = 0.24–1.72, p = 0.381), pT stage (OR = 1.16, 95% CI = 0.26–5.23, p = 0.847), serum lactate dehydrogenase level (OR = 1.06, 95% CI = 0.13–8.43, p = 0.958), or performance status (OR = 0.69, 95% CI = 0.24–1.95, p = 0.479). No significant publication bias was detected in this meta-analysis.Conclusions: This meta-analysis suggests that PD-L1 expression is not a significant prognostic factor of poor survival in SCLC. Because of significant variations, high-quality studies are needed to validate our results.
Highlights
Lung cancer remains the leading cause of cancer-related death in both men and women worldwide [1]
A total of 20 full-text articles were excluded for the following reasons: 12 lacked necessary information, three were editorials, two were letters, two did not report using an IHC method, and one was a review
The KEYNOTE-024 study [39] was not included in our meta-analysis, we suggest a uniform cutoff value of programmed cell death ligand1 (PD-L1) expression in patients with Small cell lung cancer (SCLC) to render the results of different studies more comparable
Summary
Lung cancer remains the leading cause of cancer-related death in both men and women worldwide [1]. Immune checkpoint inhibitors (ICIs) targeting programmed cell death protein-1 (PD-1)/programmed cell death ligand (PD-L1) show promising antitumor activity in patients with SCLC [5, 6]. A recent randomized, controlled, phase 3 trial showed that the combination of the PD-L1 inhibitor atezolizumab and chemotherapy as the first-line treatment results in significantly longer survival than that following chemotherapy alone in patients with extensive-stage SCLC [7]. Previous studies have investigated the prognostic role of PD-L1 in patients with SCLC, which revealed inconsistent results [8,9,10,11,12,13,14,15,16]. Previous studies have demonstrated the prognostic role of PD-L1 expression in patients with small cell lung cancer (SCLC), where the results were inconsistent. We conducted a meta-analysis to identify the prognostic impact of PD-L1 on SCLC
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